1. Field of the Invention
The present invention relates to an image forming apparatus.
2. Description of Related Art
There has been conventionally used an image forming apparatus capable of forming (or printing) an image on a recording medium such as a paper stock, based on document data read with an image reading apparatus such as a scanner or document data transmitted through a network. Moreover, in order to examine the printed state of a printed recording medium (or printed matter), there has been conventionally proposed a technique that judges the suitability of the printed state of the printed matter by comparing an image on the printed matter taken by an imaging apparatus with a previously prepared reference image and performs the coding processing of the fault information of the printed matter judged to be “wrong” to print the coded fault information at a fixed position of the printed matter (see, for example, JP2005-271431A).
Incidentally, the document data to be a print object is to be once stored in the image forming apparatus, and a part of the document data is sometimes damaged owing to a cause such as a trouble. In this case, because the aforesaid conventional technique compares the image on the printed matter that has been acquired by image pick-up with the reference image for the judgment, the conventional technique has a problem of being unable to surely judge the fault parts to be “wrong” depending on the locations or scales of the part where the data has been damaged. In particular, in booklet printing, because there is the possibility of the whole page being treated as faultily printed paper even if abnormality occurs in a part of the sheets of the printed matter composed of a plurality of pages, a technique for surely judging the abnormality of printed matter has been solicited. Moreover, because the conventional technique needs to prepare a reference image to each page in case that the print object includes a plurality of sheets of printed matter such as a booklet print, the conventional technique has another problem of the increase of the quantity of the data to be stored in advance as reference images to enlarge the cost of storage management.